1. Field of the Invention
The present invention relates to a directional control valve which allows a plurality of such directional control valves to be arrayed through manifold bases or directly on a rail.
2. Discussion of the Background
It has heretofore been practiced to array a plurality of directional control valves in a given direction and control the arrayed directional control valves in a centralized manner. For example, manifold bases are coupled respectively to directional control valves, and supported on an elongate rail for thereby arraying the directional control valves. Alternatively, a plurality of directional control valves are mounted directly on an elongate rail so as to be arrayed in the longitudinal direction of the rail.
If the plurality of directional control valves are arrayed on the rail through the manifold bases, then supply, output, and discharge ports for a fluid under pressure are defined in lower surfaces of valve bodies of the directional control valves in positions where they can communicate with corresponding openings in the manifold bases. For directly outputting the fluid under pressure from the directional control valves, the output ports are defined in upper surfaces of the valve bodies.
If the plurality of directional control valves are arrayed directly on the rail, then supply and discharge passages for a fluid under pressure are defined in the valve bodies, the supply and discharge passages extending through the valve bodies in the direction in which the valve bodies are arrayed (in the longitudinal direction of the rail). Supply and discharge ports communicating respectively with the supply and discharge passages are defined in lower surfaces of the valve bodies, and output ports are defined in upper surfaces of the valve bodies.
Even though the directional control valves have the same size and their valve body actuating means are the same as each other, their valve bodies have different structures depending on the location of the output ports, etc. for the array of directional control valves on the rail through the manifold bases and the array of directional control valves directly on the rail. Consequently, a plurality of types of valve bodies have to be made available in order to meet different arrays of directional control valves, which is not economical.